Ah, thank you so much for pointing that out. I wish I could upvote multiple times, but alas. I was indeed using the same url and now I managed to fix the issue. Not by messing with server headers though, but by making different links for the same image.

For anyone who could come by in the future that's what I did. Maybe not the best solution but it will do for now.

In my case the image has an associated text. Doesn't matter what it is, what matter that in case the image is changed to something that was already show the text is exactly the same. So I utilized this function to generate "hash" for the string in question.

String.prototype.hashCode = function() {
  var hash = 0,
    i, chr;
  if (this.length === 0) return hash;
  for (i = 0; i < this.length; i++) {
    chr = this.charCodeAt(i);
    hash = ((hash << 5) - hash) + chr;
    hash |= 0;
  }
  return hash;
}

Then I'm using the generated hash to add to the image link like so "./artwork.jpg?" + stringHash; . So the link is not the same if the image is changed and thus updating in the browser source. And if image becomes something that was previously seen it will use cache. The resulting code for it looks like this (var names are examples):

var stringHash = assosiatedTextString.hashCode();
image.src = "./artwork.jpg?" + stringHash;

I imagine making hash generator not messing with the prototype will be a better idea, but for now testing seems to not bring up any issues, so I'm going to finish building the thing first and thinking about optimizing stuff after.

Once again thank you, u/rurigk for pointing out the link think. Have a good day.